B00A0 Occupant classification sensor or control unit fault

Occupant classification system (OCS) fault

B00A0 in short

B00A0 means the airbag computer has a fault from the occupant classification system, the sensor in the front passenger seat that decides whether the passenger airbag should deploy. Nissan, Mazda and Ford bulletins tie it to a sensor reset, low battery voltage or a module link. Have it checked soon; never probe airbag wiring.

The occupant classification system senses who is in the front passenger seat and reports to the airbag computer. The airbag computer stores B00A0 when that system reports a fault, so the code points at the passenger seat sensor rather than at an airbag.

Nissan calls it the occupant classification system control unit (later the occupant detection sensor unit). For many 2009–2023 Nissan and Infiniti models, dealers check the unit with a software tool and run a zero-point reset. Mazda says B00A0:09 means the sensor's signal was unstable, which on the CX-3 and CX-5 can happen when battery voltage dips during cranking in cold weather.

Ford's bulletin for the 2021–2023 F-150 pairs B00A0 in the restraints module with communication codes from the occupant classification module. Because the passenger airbag depends on this system, treat the light as a reason to book a dealer visit soon.

Most likely causes

  1. Occupant sensor needs a zero-point reset or software check

    Supported by vehicle data
    Why it ranks here
    Nissan and Infiniti bulletins for B00A0-00 have dealers check the occupant sensor unit with a software tool and run a zero-point reset across many 2009–2023 models.
    What would change this
    Rises if the reset clears the code and it stays off. Falls if the reset cannot be completed and the unit fails the check.

  2. Low battery voltage during cranking

    Supported by vehicle data
    Why it ranks here
    Mazda's bulletins for the CX-3 and CX-5 say B00A0:09 can set when battery voltage drops during cranking, more often in cold weather, because the sensor's low-voltage detection time was too short.
    What would change this
    Rises if the light appeared on a cold morning or after a slow start and the battery tests weak. Falls if the battery and charging system test good.

  3. Communication fault between the occupant classification module and the restraints module

    Supported by vehicle data
    Why it ranks here
    Ford's F-150 bulletin pairs B00A0 in the restraints module with U3000 codes in the occupant classification module, pointing at the link between them.
    What would change this
    Rises on a 2021–2023 F-150 with U3000 stored in the occupant classification module. Falls if no U-codes are stored.

  4. Faulty occupant classification control unit or sensor

    Possible — needs testing
    Why it ranks here
    Nissan's 2015 Frontier, Xterra and Armada bulletin sends a current B00A0 to the OCS control unit diagnosis, and Nissan's training material says the repair for OCS unit faults is the passenger seat cushion assembly.
    What would change this
    Rises if resets and battery checks do not clear a current code. Falls if a reset or software fix clears it.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Have the airbag codes read with a scan tool, including the number after B00A0 and any codes stored in the occupant classification module.

    Low riskTool: scan tool with airbag (SRS) access

  2. Have the 12-volt battery and charging system tested.

    Low riskTool: battery tester

  3. Have a dealer check the occupant classification system with the maker's software and run any reset or update the bulletins call for.

    Best left to a shopTool: maker's diagnostic tool

    Warning:Never probe airbag connectors or wiring with a test light or meter, and never unplug them yourself. Nissan warns that airbags and pretensioners can still deploy after the ignition is off, and that test equipment must not be used on airbag circuits unless the service manual calls for it. Leave this to a dealer or trained technician.

Symptoms

  • Airbag warning light on
  • Airbag light comes on after a cold start or slow crank
  • Passenger airbag status light shows the airbag off with an adult in the seat

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

  • Occupant classification sensor and control unit:Several makers fix B00A0 with a reset, software update or battery check before replacing parts. On Nissan the sensor is part of the passenger seat cushion assembly. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

  • 2009–2023 · Rogue

    Supported by vehicle data

    Nissan's bulletin for B00A0-00 checks the OCS unit with software and runs a zero-point reset before any parts are replaced. Whether it is still current is not verified.

  • 2015 · Frontier

    Supported by vehicle data

    Nissan's bulletin sends a current B00A0 to the service manual's OCS control unit diagnosis. Whether it is still current is not verified.

  • NTB19-071CStatus unverified

    DTC B00A0-00 stored

    2009–2023rogue, pathfinder, murano, maxima, versa, frontier · issued · NHTSA 10234044

    When B00A0-00 is stored and the zero-point reset cannot be done, check the OCS control unit with Nissan's analysis software and run the reset procedure.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • NTB14-096Status unverified

    DTC B00A0 (occupant classification system control unit)

    2015frontier, xterra, armada · issued · NHTSA 10056482

    If B00A0 is current in the airbag computer, follow the service manual's OCS control unit diagnosis.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Infiniti

  • 2014–2020 · Q50

    Supported by vehicle data

    Infiniti's bulletin for B00A0-00 matches Nissan's: software check and zero-point reset. Whether it is still current is not verified.

  • ITB19-024Status unverified

    DTC B00A0-00 stored

    2009–2020q50, qx60, qx80 · issued · NHTSA 10165750

    Infiniti version of Nissan's bulletin: check the occupant sensor unit with the analysis software and run the zero-point reset.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ford

  • 2021–2023 · F-150

    Supported by vehicle data

    Ford's bulletin covers an airbag light with B00A0 in the restraints module and U3000 in the occupant classification module. Whether it is still current is not verified.

  • TSB 25-2465Status unverified

    Airbag light with U3000 in the OCSM and/or B00A0 in the RCM

    2021–2023f-150 · issued · NHTSA 11024198

    Supersedes TSB 23-2280. Gives the repair for an airbag light with these codes.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Mazda

  • 2016–2020 · CX-5

    Supported by vehicle data

    Mazda links B00A0:09 to low battery voltage during cranking, especially in colder weather. Whether the bulletin is still current is not verified.

  • 2016–2020 · CX-3

    Supported by vehicle data

    Same Mazda bulletin as the CX-5: B00A0:09 from low cranking voltage. Whether it is still current is not verified.

  • 08-002-23Status unverified

    Airbag warning light with B00A0:09

    2016–2020cx-3, cx-5 · issued · NHTSA 10232280

    Addresses B00A0:09 set when battery voltage is low during cranking; the sensor's low-voltage detection time was too short.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • U3000Manufacturer code: on Ford, Honda, Acura and Mazda, the module that stored it found a fault inside itself

    Shares causes Supported by vehicle data

    Ford's 2021–2023 F-150 bulletin pairs B00A0 in the restraints module with U3000 in the occupant classification module, pointing at the link between the two modules.

  • B1018Passenger seat occupant sensor mat malfunction (Nissan)

    Same system Supported by vehicle data

    B1018 is Nissan's code for the occupant classification sensor mat in the same passenger seat system. Nissan's training material says the repair for these parts is the passenger seat cushion assembly.

  • B0081Passenger presence (seat occupant sensing) system fault

    Same system Common general cause

    B0081 is GM's passenger presence system fault. Like the occupant classification system, it senses who is in the passenger seat and reports to the airbag computer, which can switch off the passenger airbag.

All Airbags and seat-belt restraints (SRS) codes

B00A0 questions

Can a weak battery cause B00A0?

On some Mazda CX-3 and CX-5 models, yes. Mazda says B00A0:09 can set when battery voltage drops during cranking in cold weather. Have the battery tested.

Sources and review

  1. 2023 Accord Owner's Manual: Airbag System Indicators — American Honda Motor Co.
  2. Camry Owner's Manual (OM06291U) — Toyota
  3. NTB19-071: DTC B00A0-00 (occupant detection sensor unit) stored and OCS zero point reset cannot be performed — Nissan North America / NHTSA ,
  4. NTB19-071C: DTC B00A0-00 stored (amended) — Nissan North America / NHTSA ,
  5. ITB19-024: DTC B00A0-00 (occupant detection sensor unit) stored — Nissan North America (Infiniti) / NHTSA ,
  6. 08-001-20: airbag warning light with DTC B00A0:09 when battery voltage is low (CX-3, CX-5) — Mazda North American Operations / NHTSA ,
  7. 08-002-23: airbag warning light with DTC B00A0:09 (CX-3, CX-5) — Mazda North American Operations / NHTSA ,
  8. TSB 25-2465: airbag indicator with U3000 in the OCSM and/or B00A0 in the RCM (supersedes TSB 23-2280) — Ford Motor Company / NHTSA ,
  9. NTB14-096: DTC B00A0 (occupant classification system control unit) current in the airbag diagnosis sensor unit (2015 Frontier, Xterra, Armada) — Nissan North America / NHTSA ,
  10. Nissan Supplemental Restraint Systems: damage analysis and repair using Diagnostic Trouble Codes (TechNews, Summer 2016) — Nissan North America ,
  11. DTC B0081 (SDM): 2011 Saab 9-4X workshop information — Saab Automobile / General Motors
Last reviewed
Written by
Saurabh K.
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